The present invention relates to a wiper apparatus for wiping a curved vehicular window.
There have been developed wiper apparatuses including wiper blades suitable for wiping curved surfaces of glass windows. These wiper blades are preferably disposed on the curved surfaces at desired angles. One example of such wiper apparatuses is disclosed in Japanese Patent No. 2707817. The disclosed wiper apparatus has a wiper blade including a rubber housing member. The rubber holding member has a twisted blade rubber mounted thereto. The twisted blade rubber has one end inclined a given angle away from a vertical line. Another end of the blade rubber is inclined another given angle away from the vertical line. FIG. 16 hereof shows the wiper apparatus disclosed in the aforementioned Japanese Patent. In wiping a curved windshield surface 102 at a particular position Q, the blade rubber of the wiper blade designated 101 has a center part B inclined an angle xcex52 (=xcex1) away from a line (hereinafter referred to as xe2x80x9cnormalxe2x80x9d) extending perpendicularly to the windshield. Proximal and distal ends A, C of the blade rubber of the wiper blade 101 at the position Q are inclined angles xcex51, xcex53 (=xcex1) away from the normal. For ease of explanation, an angle the wiper blade 101 or the blade rubber is inclined away from the normal is hereinafter referred to as xe2x80x9cerror anglexe2x80x9d.
As discussed above, when positioned at the position Q, the blade rubber of the wiper blade 101 provides a constant error angle (=xcex1) along the entire length thereof. With the error angles xcex51, xcex52, xcex53 close to each other, the wiper blade wipes the surface 102 efficiently.
As shown in FIG. 16, the wiper blade 101 pivots an angle U or moves back and forth between a stop position G and a turning position H to wipe the surface 102. An intermediate position D is located midway between the stop position G and the turning position H.
With respect to FIG. 17A through FIG. 17C hereof, the center part B and the proximal and distal ends A, C of the blade rubber designated 103 are shown as being disposed as the position Q. Likewise, in FIG. 18A through FIG. 18C hereof, the center part B and the proximal and distal ends A, C are shown as being disposed at the intermediate position D.
Referring to FIG. 17B, the wiper blade 101 has the error angle xcex52 (=xcex1) at the center part B. At the proximal and distal ends A, C, as shown in FIG. 17A and FIG. 17C, there are provided the error angles xcex51, xcex53 equal to the error angle xcex52. This arrangement enables the wiper blade 101 to wipe the position Q and its surroundings with increased efficiency.
When disposed at positions other than the position Q, however, the blade rubber provides different error angles along the entire length thereof. The error angle of the blade rubber 103, disposed especially at the turning position H, significantly varies along its length.
Reference is made to FIG. 18B. The center part B has the error angle xcex52 which is 2.5 times the angle xcex1. The error angle xcex51 of the proximal end A is 3 times the angle xcex1, as shown in FIG. 18A. The distal end C provides the error angle xcex53 which is twice the angle xcex1, as shown in FIG. 18C. As can be seen from these figures, there is a significant difference in error angle between the proximal end A, the center part B and the distal end C of the blade rubber 103 located at the position D. Accordingly, some materials to be wiped off would be unfortunately left on the curved surface 102 of the windshield.
An object of the present invention is to provide a wiper apparatus including a blade rubber which, when moving over a curved surface of a glass window, is directed perpendicularly thereto, such that the curved surface is evenly wiped throughout.
According to an aspect of the present invention, there is provided a wiper apparatus comprising: (A) a drive shaft; (B) an arm head connected to the drive shaft; (C) an arm extending from the arm head, the arm being pivotable about the drive shaft; and (D) a wiper blade mounted to the arm and extending in substantially parallel to the arm; the wiper blade including: (a) a primary lever; (b) plural blade holding members mounted to the primary lever, the blade holding members being disposed in alignment; (c) a blade rubber mounted to the blade holding members; the blade holding members each including: (i) a pivotal member; (ii) a twisting member fixed to the pivotal member; (iii) a non-pivotal member connected to the pivotal member in such a manner that the twisting member causes the pivotal member to pivot in a lateral direction of the primary lever in response to the pivotal movement of the arm.
The pivotal member is pivotally connected to the non-pivotal member. The pivotal member and the non-pivotal member are provided in alignment. The twisting member is arranged to cause the pivotal member to point in the lateral direction of the primary lever in response to the pivotal movement of the arm. The pivotal movement of the pivotal member twists the blade rubber. The thus twisted blade rubber has its opposite ends disposed on a curved windshield at right angles thereto. During the pivotal movement of the arm, the opposite ends of the blade rubber maintain a substantially perpendicular relation to the windshield. The wiper apparatus thus arranged provides an improved ability to wipe the windshield. In other words, there can be achieved an improved performance of the wiper apparatus for wiping the windshield.
In a preferred form of the present invention, the twisting member comprises a sub-arm pivotable on a support shaft spaced from the drive shaft by a given distance, and a cam connected to the sub-arm, the sub-arm causing the cam to pivot in such a manner that the pivotal member pivots in the lateral direction of the primary level.
The twisting member is formed by the small number of parts, i.e., the sub-arm and the cam. Providing such a twisting member helps manufacture the wiper apparatus at a low cost.